stat: avoid hang with race in stat thread exit and rusage update

Signed-off-by: Jens Axboe <axboe@fb.com>

2 files changed, 13 insertions, 4 deletions

diff --git a/backend.c b/backend.c
index 4437d196..90d998dc 100644
--- a/backend.c
+++ b/backend.c
@@ -1564,13 +1564,17 @@ err:
 	if (o->write_iolog_file)
 		write_iolog_close(td);
 
-	fio_mutex_remove(td->rusage_sem);
-	td->rusage_sem = NULL;
-
 	fio_mutex_remove(td->mutex);
 	td->mutex = NULL;
 
 	td_set_runstate(td, TD_EXITED);
+
+	/*
+	 * Do this last after setting our runstate to exited, so we
+	 * know that the stat thread is signaled.
+	 */
+	check_update_rusage(td);
+
 	return (void *) (uintptr_t) td->error;
 }
 
@@ -2097,8 +2101,11 @@ int fio_backend(void)
 		}
 	}
 
-	for_each_td(td, i)
+	for_each_td(td, i) {
 		fio_options_free(td);
+		fio_mutex_remove(td->rusage_sem);
+		td->rusage_sem = NULL;
+	}
 
 	free_disk_util();
 	cgroup_kill(cgroup_list);
diff --git a/stat.c b/stat.c
index a5fd50b9..3aae76df 100644
--- a/stat.c
+++ b/stat.c
@@ -1451,6 +1451,8 @@ static void __show_running_run_stats(void)
 	}
 
 	for_each_td(td, i) {
+		if (td->runstate >= TD_EXITED)
+			continue;
 		if (td->rusage_sem) {
 			td->update_rusage = 1;
 			fio_mutex_down(td->rusage_sem);